DE102013203429B4 - Method for illuminating an environment, lighting device and camera with lighting device - Google Patents

Abstract

A method of illuminating an electromagnetic radiation environment wherein a correlated color temperature (501) of an ambient light is determined, wherein a spectral power of the electromagnetic radiation is selected such that an integral of the spectral power has a nominal value over a wavelength interval between 380 nm and 780 nm in that an integral of the spectral power has a first value over a wavelength interval between 420 nm and 460 nm, an integral of the spectral power has a second value over a wavelength interval between 510 nm and 550 nm, an integral of the spectral power over a wavelength interval between 580 nm and 620 nm has a third value, the ratio (305) of the first value to the nominal value between the sum of -4.13 × 10-2 and the product of +1.96 × 10-5 / K and the correlated color temperature (501 ) and the sum of + 5.63 × 10-2 and the product of + 3.91 × 10-5 / K and the corr color temperature (501), the ratio (306) of the second value to the nominal value between the sum of +7.66 x 10-2 and the product of +7.55 x 10-6 / K and the correlated color temperature (501) and the sum of +2.08 × 10-1 and the product of +9.87 × 10-6 / K and the correlated color temperature (501), and the ratio (307) of the third value to the nominal value between the sum of +1.40 x 10-1 and the product of -5.77 x 10-6 / K and the correlated color temperature (501) and the sum of +3.45 x 10-1 and the product of -2.06 x 10-5 / K and the correlated color temperature (501).

Description

The present invention relates to a method for illuminating an environment with electromagnetic radiation according to claim 1, a lighting device according to claim 4, and a camera with a lighting device according to claim 8.

It is known to provide cameras with flash devices in order to additionally illuminate scenes to be recorded by the camera in the event of insufficient lighting conditions. This improves a signal-to-noise ratio. It is known to provide such flash devices with discharge lamps. Also known are flash devices that have one or more light emitting diodes (LEDs). Such flash devices are used in particular in miniaturized cameras, as provided for example in mobile phones. However, known flash devices with LEDs are not optimized for color reproduction.

An object of the present invention is to provide a method for illuminating an environment with electromagnetic radiation. This object is achieved by a method having the features of claim 1. Another object of the present invention is to provide a lighting device. This object is achieved by a lighting device having the features of claim 4. Another object of the present invention is to provide a camera with a lighting device. This object is achieved by a camera having the features of claim 8. In the dependent claims various developments are given.

In a method for illuminating an environment with electromagnetic radiation, a correlated color temperature of an ambient light is determined. In this case, a spectral power of the electromagnetic radiation is selected such that an integral of the spectral power over a wavelength interval between 380 nm and 780 nm has a nominal value, an integral of the spectral power has a first value over a wavelength interval between 420 nm and 460 nm Integral the spectral power over a wavelength interval between 510 nm and 550 nm has a second value, an integral of the spectral power over a wavelength interval between 580 nm and 620 nm has a third value, the ratio of the first value to the nominal value between the sum of -4 , 13 × 10 ^-2 and the product of +1.96 × 10 ^-5 / K and the correlated color temperature and the sum of +5.63 × 10 ^-2 and the product of + 3.91 × 10 ^-5 / K and the correlated color temperature, the ratio of the second value to the nominal value between the sum of + 7.66 × 10 ^-2 and the product of + 7.55 × 10 ^-6 / K and the correlated color temperature and the sum of +2.08 × 10 ^-1 and the product of +9.87 × 10 ^-6 / K and the correlated color temperature, and the ratio of the third value to the nominal value between the sum of +1.40 × 10 ^-1 and the product of -5.77 × 10 ^-6 / K and the correlated color temperature and the sum of + 3.45 × 10 ^-1 and the product of -2.06 × 10 ^-5 / K and the correlated color temperature is. Advantageously, the environment is illuminated in this method with electromagnetic radiation whose spectral power is distributed so that a photographic image of the illuminated environment reproduces colors similar to those perceived by an immediate observer of the environment. The spectral power distribution of the electromagnetic radiation used to illuminate the environment is in particular dimensioned such that a corruption of the color reproduction caused by color filters of a camera and by a white balance performed by the camera is compensated. Photographs of a process illuminated environment may advantageously have good color reproduction.

In one embodiment of the method, the spectral power of the electromagnetic radiation is selected such that the ratio of the first value to the nominal value is between the sum of -2.13 × 10 ^-2 and the product of +1.96 × 10 ^-5 / K and the correlated color temperature and the sum of +1.63 × 10 ^-2 and the product of + 3.91 × 10 ^-5 / K and the correlated color temperature, the ratio of the second value to the nominal value between the sum of + 9.66 × 10 ^-2 and the product of +7.55 × 10 ^-6 / K and the correlated color temperature and the sum of +1.78 × 10 ^-1 and the product of + 9.87 × 10 ^-6 / K and the correlated color temperature, and the ratio of the third value to the nominal value between the sum of +1.52 × 10 ^-1 and the product of -5.77 × 10 ^{- 6} / K and the correlated color temperature and the sum of + 3.19 × 10 ^-1 and the product of -2.06 × 10 ^-5 / K and the correlated color temperature. Advantageously, the electromagnetic radiation used to illuminate the environment then has a particularly optimized spectral power distribution, whereby a photograph of the environment can have a further improved color reproduction.

In one embodiment of the method, the spectral power of the electromagnetic radiation is selected such that the ratio of the first value to the nominal value between the sum of -1.30 × 10 ^-3 and the product of + 1.96 × 10 ^-5 / K and the correlated color temperature and the sum of -2.37 × 10 ^-2 and the product of + 3.91 × 10 ^-5 / K and the correlated color temperature, the ratio of the second value to the nominal value is between the sum of +1.17 × 10 ^-1 and the product of +7.55 × 10 ^-6 / K and the correlated color temperature and the sum of +1.48 × 10 ^-1 and the product of +9.87 × 10 ^-6 / K and the correlated color temperature, and the ratio of the third value to the nominal value between the sum of +1.64 x 10 ^-1 and the product of -5.77 x 10 ^-6 / K and the correlated color temperature and the sum of +2.93 × 10 ^-1 and the product of -2.06 × 10 ^-5 / K and the correlated color temperature. Advantageously, the electromagnetic radiation used for illuminating the environment then has an even more optimized spectral power distribution, as a result of which a photograph of the surroundings can have a further improved color reproduction.

A lighting device is designed to perform a method of the aforementioned type. Advantageously, the illumination device is thereby suitable for illuminating an environment which is to be photographically recorded by means of a camera. The illumination device can illuminate the environment in such a way that colors of the surroundings are reproduced with high color fidelity in a photograph of the environment. The illumination device can illuminate the surroundings in such a way that color falsifications caused by a photographic camera, in particular color falsifications by color filters of the camera, are compensated.

In one embodiment of the lighting device, this has a light-emitting diode. Advantageously, the lighting device can thereby be made compact and inexpensive. In addition, the lighting device has only a low energy consumption.

In one embodiment of the lighting device, this has at least two light-emitting diodes. Advantageously, electromagnetic radiation emitted by the at least two light-emitting diodes of the illumination device can be mixed such that a superimposition of the electromagnetic radiation has a favorable spectral power distribution.

In one embodiment of the illumination device, it has a sensor for detecting an ambient light.

Advantageously, the sensor for detecting the ambient light allows a consideration of a correlated color temperature of the ambient light in an illumination of an environment by the lighting device.

A camera has a lighting device of the aforementioned type. Advantageously, the illumination device may be used to illuminate a scene taken with the camera, thereby improving a signal-to-noise ratio in the photographic capture of the scene. The lighting of the scene by the lighting device may also cause an improved color reproduction of the captured with the camera recording of the scene.

In one embodiment of the camera, the lighting device is designed as a flash device. Advantageously, the illumination device thereby enables illumination of an environment of the camera at a time at which a photographic image of the surroundings is made with the camera.

In one embodiment of the camera, this has a digital image sensor. Advantageously, the camera thereby enables the production of digital photographic images.

In one embodiment of the camera, this is designed as a mobile phone. Advantageously, the camera then has several functions, which increases the usefulness of the camera.

The above-described characteristics, features, and advantages of this invention, as well as the manner in which they will be achieved, will become clearer and more clearly understood in connection with the following description of the embodiments, which will be described in detail in conjunction with the drawings. Show

1 a highly schematic representation of a photographic imaging process compared to an immediate perception of a scene;

2 a spectral diagram with a representation of favorable spectral power distributions;

3 an RGB filter space diagram to compare cheaper and less favorable spectra;

4 a first ambient light spectrum chart comparing favorable and less favorable spectra;

5 a second ambient light spectrum chart comparing favorable and less favorable spectra;

6 a third ambient light spectrum chart comparing favorable and less favorable spectra;

7 a first spectrum spectrum chart comparing favorable and less favorable spectra;

8th a second spectrum spectrum chart comparing favorable and less favorable spectra;

9 a third spectrum spectrum chart comparing favorable and less favorable spectra;

10 a first characterization diagram for characterizing favorable spectra;

11 a second characterization diagram for characterizing favorable spectra;

12 a third characterization diagram for characterizing favorable spectra; and

13 a highly schematic representation of a camera with a lighting device.

1 shows a highly schematic representation for explaining color deviations that may arise when creating photographic images of a scene.

A human viewer 130 looks at a scene 100 , The scene 100 For example, it may be located in a building or outdoors. The scene 100 may include an object, a landscape, or, for example, a color chart with one or more defined test colors.

The scene 100 is from an ambient light 110 illuminated. If the scene 100 arranged in the wild, so can the ambient light 110 For example, be daylight, such as bright sunshine in a cloudless sky, the light of a cloudy sky or evening twilight. If the scene 100 is arranged in a closed room, so can the ambient light 110 For example, be the light of an incandescent lamp, a halogen lamp, a fluorescent lamp or a discharge lamp. The ambient light 110 has different spectral compositions in each case. Approximately the ambient light 110 by specifying a correlated color temperature of the ambient light 110 be characterized.

The contemplation of the scene 100 by the viewer 130 leads the viewer 130 for a first impression 131 , The first impression 131 indicates how the viewer is 130 those in the scene 100 perceives contained colors. The color perception of the viewer 130 depends on the spectral composition of the scene 100 to the viewer 130 reflected light, ie of the physical wavelengths of a retina of the viewer 130 impinging photons. Next to it will be the first impression 131 the viewer 130 but also determined by a physiological component. The color receptors of the observer are better able to resolve colors in some wavelength ranges than in others. In addition, the eyes of the beholder adapt 130 to the color temperature of the ambient light 110 that the scene 100 illuminated.

By using a color appearance model, such as the CIECAM02 model, the viewer can 130 resulting first impression 131 the scene 100 mathematically modeled. The color appearance model makes it possible to obtain from a knowledge of the spectral composition of the ambient light 110 and the reflection characteristics of one in the scene 100 contained color, such as a defined test color, the viewer 130 resulting first impression 131 to be calculated.

1 further shows a schematic representation of operations in creating and viewing a photographic image of the scene 100 , The scene 100 is with a camera 140 photographed or filmed. The camera 140 may be, for example, a digital camera. In this case, a camera sensor (image sensor) of the camera 140 a color filter 141 upstream of the scene 100 on the camera chip of the camera 140 incident light filters. Further, the camera leads 140 a white balance 142 through which it tries to have different color temperatures of the ambient light 110 to compensate. Both the color filters 141 as well as the white balance 142 the camera 140 lead to a falsification of the camera 140 photographically captured colors of the scene 100 ,

That from the camera 140 recorded photographic image of the scene 100 can by the viewer 130 by means of a monitor 150 to be viewed as. Also the monitor 150 could cause a color corruption. However, below is an ideal monitor 150 assumed, which causes no further color distortion.

While looking at the picture of the scene 100 on the monitor 150 The eyes of the beholder adapt 130 to an ambient light prevailing at that time. The viewing of the camera 140 recorded image of the scene 100 leads the viewer 130 for a second impression 132 , The second impression 132 indicates how the viewer is 130 in the picture of the scene 100 perceives contained colors. Because of the described color distortions corresponds to the second impression 132 usually not the first impression 131 , Opposite the direct view of the scene 100 it will appear on the monitor 150 illustrated illustration of the scene 100 the viewer 130 with a wrong color reproduction.

Are in addition to the spectral composition of ambient light 110 and the reflection characteristics of in the scene 100 Colors also include the physical filter characteristics of the color filter 141 and the characteristics of the camera 140 performed white balance 142 For example, from measurements, known, so can the viewer 130 while looking at the picture of the scene 100 resulting second impression 132 be modeled by using a color appearance model. The color appearance model allows, taking into account the mentioned influencing parameters, a mathematical determination of the perception of color that occurs in the viewer 130 looking at a picture of one in the scene 100 contained color results. Thus, the color perception model also allows quantification of a difference between the first impression 131 the viewer 130 when viewing the scene directly, and the second impression 132 the viewer 130 considering the photographic image of the scene 100 receives.

The camera 140 may have a flashing device around the scene 100 while making a recording of the scene 100 , in addition to illumination with ambient light 110 , with a flash 120 to illuminate. Depending on the spectral composition of the flash 120 the spectral composition of the scene changes 100 to the camera 140 reflected light. This also changes the ones in the picture of the scene 100 contained and on the monitor 150 shown colors, which also gives the second impression 132 the viewer 130 depending on the spectral composition of the flash 120 changes. The spectral composition of the flash 120 can be chosen so that the resulting second impression 132 the smallest possible deviation from the first impression 131 having.

In a systematic investigation can flashlights 120 with different spectral composition are compared with each other to obtain an optimum spectral composition of the flash 120 to investigate. For each spectrum, for a number of, for example, 84 defined test colors using the described models, respectively, the viewer can 130 direct impression resulting first impression 131 and the second impression resulting from viewing a photograph 132 the test color are calculated. The color difference between the first impression 131 and the second impression 132 can be summed up for all test colors. The sum of the color differences provides a measure of when using a flashlight 120 with the respective spectrum adjusting color deviation.

Another criterion for assessing the suitability of an examined spectral composition of the flash 120 is in the camera 140 performed white balance 142 , Indicates that through the camera 140 performed white balance 142 Matrix elements which are large relative to the other matrix elements result in a large amplification of noise signals of the camera sensor of the camera 140 , which improves the quality of the camera 140 made recording sinks. The spectrum of the flashlight 120 should be chosen so that by the camera 140 performed white balance 142 no too large matrix elements emerge.

From the above criteria for assessing the suitability of a spectral composition of the flash 120 can be a valuation function (merit value) form. The weighting function can be considered as the sum of the maximum white balance matrix element 142 and 0.01 times the color difference between the first impression added over all the test colors 131 and the second impression 132 To be defined. With a favorable spectrum of the flashlight 120 this rating function has a low value. By comparing different spectrums of the flashlight 120 at different correlated color temperatures of the ambient light 110 can be used for any correlated color temperature of the ambient light 110 favorable spectrums of the flashlight 120 identify.

2 shows an exemplary spectral diagram 400 in which spectrums of the flashlight 120 are shown, which are suitable for ambient light 110 with a correlated color temperature of 3200K have proved favorable. On a horizontal axis of the spectral diagram 400 is a wavelength 401 in nm. On a vertical axis of the spectral diagram 400 is a spectral power 402 applied in 10 ^-6 W / nm. Shown are a number of spectra 210 , These spectra 210 have compared to other spectra as favorable spectra 211 proven, so have small values of the above-defined evaluation function.

For other correlated color temperatures of ambient light 110 can be correspondingly favorable spectra 211 find. It turns out that favorable spectra 211 each have characteristic common properties. The characteristic properties of favorable spectra 211 can be expressed in different ways, as shown below.

The favorable spectra 211 can in the RGB filter space of the color filter 141 the camera 140 be characterized. For this purpose, the R, G and B signals are determined, which result when light of the examined spectral composition directly on the camera 140 is directed. 3 shows an exemplary RGB filter space diagram 200 , as is the case with ambient light 110 with a correlated color temperature of 3200K. On a horizontal axis of the RGB filter space diagram 200 is a red component 201 of the resulting RGB signal in units of R / (R + G + B). On a vertical axis of the RGB filter space diagram 200 is a blue component 202 of the resulting RGB signal in units of B / (R + G + B). Each spectrum examined 210 of the flashlight 120 makes a point in the RGB filter space diagram 200 , Cheap spectra 211 , which have a low value of the evaluation function, are grouped in the exemplary RGB filter space diagram 200 at lower values of the vertical axis as unfavorable spectra 213 with high value of the evaluation function.

Corresponding diagrams can also be used for favorable spectra 211 at other correlated color temperatures of the ambient light 110 to be created. In summary, it turns out that the reds 201 and the blue parts 202 of favorable spectra 211 at correlated color temperatures of the ambient light 110 2800K, 3200K, 4500K, 5500K, 6500K and 8500K in the following ranges: 2800K 3200K 4500K 5500K 6500K 8500K R / (R + G + B) 0.38 to 0.44 0.35 to 0.41 0.28 to 0.34 0.25 to 0.31 0.23 to 0.29 0.21 to 0.27 B / (R + G + B) 0.16 to 0.22 0.18-0.25 0.24 to 0.3 0.28 to 0.34 0.3-0.36 0.34 to 0.4

Cheap spectra 211 of the flashlight 120 may also be different in their spectral components in different wavelength ranges relative to the spectral components of the ambient light 110 be characterized in the different wavelength ranges. For this, the following variables can be defined:

Here s _flash (λ) are dependent on the wavelength λ spectral power of the flash 120 and s _environment (λ) the wavelength-dependent spectral power of the ambient light 110 ,

4 shows an exemplary first on the ambient light 110 related spectrum diagram 300 , The first spectrum diagram 300 applies to ambient light 110 with a correlated color temperature of 3200K. On a horizontal axis of the first spectrum diagram 300 is a rating 301 , that is the value of the valuation function defined above. On a vertical axis of the first spectrum diagram 300 is a first relative spectral power 302 plotted as the value (F ₁ U _tot ) / (F _ges U ₁ ). Each spectrum examined 210 is by a dot in the first spectrum chart 300 represents. Cheap spectra 211 with lower value of the weighting function are left in the first spectrum chart 300 , Unfavorable spectra 213 with a high value of the evaluation function are in the first spectrum diagram 300 right. In between there are mediocre spectra 212 with mean values of the evaluation function. The first relative spectral power 302 lies with favorable spectra 211 in a characteristic interval.

5 shows an exemplary second on the ambient light 110 related spectrum diagram 310 , The second spectrum diagram 310 again applies to ambient light 110 with a correlated color temperature of 3200K. On a horizontal axis of the second on the ambient light 110 related spectrum diagram 310 is the rating 301 , so the value of the evaluation function, plotted. On a vertical axis of the second spectrum diagram 310 is a second relative spectral power 303 plotted by the expression (F ₂ U _tot ) / (F _ges U ₂ ). Each spectrum examined 210 becomes in the second spectrum diagram 310 represented by a dot. Cheap spectra 211 can be found in the left area of the second spectrum of the second spectrum diagram 310 , Unfavorable spectra 213 become by dots in the right part of the second spectrum chart 310 shown. In between there are mediocre spectra 212 , The second relative spectral power 303 lies with favorable spectra 211 in a characteristic interval.

6 shows an exemplary third on the ambient light 110 related spectrum diagram 320 , The third spectrum diagram 320 refers to ambient light with a correlated color temperature of 3200K. On a horizontal axis of the third spectrum diagram 320 is the rating 301 applied. On a vertical axis of the third spectrum diagram 320 is a third relative spectral power 304 plotted by the expression (F ₃ U _ges ) / (F _ges U ₃ ). Cheap spectra 211 are represented by dots in the left area of the third spectrum chart 320 represents. Mediocre spectra 212 are as points in the middle of the third spectrum diagram 320 shown. Unfavorable spectra 213 with high weighting function are indicated by dots in the right area of the third spectrum chart 320 shown. The third relative spectral power 304 lies with favorable spectra 211 in a characteristic interval.

To the spectrum charts 300 . 310 . 320 of the 4 to 6 Analog spectrum diagrams can be used for ambient light 110 make with other correlated color temperatures than 3200K. From these spectrum diagrams can be general properties of favorable spectra 211 read off. The properties of favorable spectra 211 with low weighting function can be summarized as follows: 2800K 3200K 4500K 5500K 6500K 8500K (F ₁ U _tot ) / (F _tot U ₁ ) 1.6 to 4.2 1.6-3 1.2-2.6 1 to 2.4 1-2.2 1-2.2 (F ₂ U _tot ) / (F _tot U ₂ ) 1.9-2.7 1.7-2.4 1.4-2 1.3-1.9 1.3-1.9 1.2-1.9 (F ₃ U _tot ) / (F _tot U ₃ ) 1.4-2.5 1.3-2.2 1.2-1.8 1.2-1.8 1.1-1.7 1.1-1.7

For example, it can be seen from the table given that, given a favorable spectrum 211 of the flashlight 120 in ambient light 110 with a correlated color temperature of 4500K the second relative spectral power 303 (F ₂ U _ges ) / (F _ges U ₂ ) should be between 1, 4 and 2.

A characterization of favorable spectra 211 of the flashlight 120 is also possible in terms of their spectral components in limited wavelength intervals with respect to the respective total spectrum.

7 shows by way of example a first spectrum diagram relating to the respective overall spectrum 330 , The first spectrum spectrum related spectrum chart 330 applies to ambient light 110 with a correlated color temperature of 3200K. On a horizontal axis of the first spectrum spectrum spectrum diagram 330 is the rating again 301 of the respective spectrum 210 applied. On a vertical axis of the first spectrum diagram related to the respective total spectrum 330 is a first proportionate spectral power 305 applied. This is defined by the expression F ₁ / F _ges . Each spectrum examined 210 is by a point in the first spectrum spectrum spectrum diagram 330 represents. Cheap spectra 211 can be found in the left area of the diagram 330 , Mediocre spectra 212 are in the middle part of the diagram 330 shown. Unfavorable spectra 213 are by dots in the right part of the first spectrum spectrum spectrum chart 330 shown. The first proportional spectral power 305 lies with favorable spectra 211 in a characteristic interval.

8th shows an exemplary second related to the respective total spectrum spectrum diagram 340 , Also the second spectral diagram related to the respective total spectrum 340 applies to ambient light 110 with a correlated color temperature of 3200K. On a horizontal axis is again the rating 301 applied. On a vertical axis is a second proportionate spectral power 306 plotted, which is defined by the expression F ₂ / F _ges . Cheap spectra 211 with low rating 301 , that is, low value of the weighting function, are in the left-hand area of the second spectrum-related spectrum chart 340 shown. Mediocre spectra 212 are found in the middle part of the second spectrum spectrum spectrum diagram 340 , Unfavorable spectra 213 are in right-hand section of the second spectrum-related spectrum diagram 340 shown. The second proportional spectral power 306 lies with favorable spectra 211 in a characteristic interval.

9 shows an exemplary third spectrum spectrum related to the respective total spectrum 350 , Also the third spectrum spectrum related spectrum chart 350 applies to ambient light 110 with a correlated color temperature of 3200K. On a horizontal axis is again the rating 301 the examined spectra 210 applied. On a vertical axis is a third proportionate spectral power 307 represented by the expression F ₃ / F _ges . Cheap spectra 211 with low value of the weighting function can be found in the left part of the diagram 350 , Unfavorable spectra 213 are in the right part of the diagram 350 shown. In between there are mediocre spectra 212 , The third proportional spectral power 307 lies with favorable spectra 211 in a characteristic interval.

From the spectral diagrams related to the respective overall spectrum 330 . 340 . 350 of the 7 to 9 and from each analogue diagrams for ambient light 110 with other correlated color temperatures common properties of favorable spectra can be determined 211 read off with a low value of the evaluation function. The thus discovered common properties of favorable spectra 211 can be used for different correlated color temperatures of the ambient light 110 as summarized in the following table: 2800K 3200K 4500K 5500K 6500K 8500K F ₁ / F _tot 0.04-0.09 0.05-0.12 0.08-0.18 from 0.1 to 0.23 0.12 to 0.26 0.14 to 0.29 F ₂ / F _tot 0.12-0.18 0.13 to 0.19 0.15 to 0.22 0.15 to 0.23 from 0.16 to 0.23 from 0.16 to 0.23 F ₃ / F _tot 0.14 to 0.28 0.14 to 0.25 0.13 to 0.21 0.13-0.18 0.12 to 0.17 0.11-0.15

The table shows, for example, that in ambient light 110 with a correlated color temperature of 6500K flash 120 with a favorable spectrum 211 a second proportional spectral power defined by the expression F ₂ / F _ges 306 between 0.16 and 0.23.

10 shows a schematic first characterization diagram 500 for further characterization of the favorable spectra 211 , On a horizontal axis of the first characterization diagram 500 is a correlated color temperature 501 the ambient light 110 applied in K. On a vertical axis of the first characterization diagram 500 is the first proportional spectral power 305 a spectrum 210 of the flashlight 120 applied.

A first lower limit 510 represents the values given in the table above of the lower limit of the first proportional spectral power 305 the favorable spectra 211 at different values of the correlated color temperature 501 the ambient light 110 exhibit. A first upper limit 511 represents the corresponding maximum values of the first proportionate spectral power 305 at favorable spectra 211 represents.

First lower interval limits 520 . 530 . 540 approach that of the correlated color temperature 501 dependent course of the first lower limit 510 linear. First upper interval limits 521 . 531 . 541 approach that of the correlated color temperature 501 dependent course of the first upper limit 511 linear. The ranges between the first lower interval limits 520 . 530 . 540 and the first upper interval limits 521 . 531 . 541 approach that for favorable spectra 211 possible value range of the first proportional spectral power 305 between the first lower limit 510 and the first upper limit 511 different tight.

The first far lower interval limit 520 is defined by the function 1.96 × 10 ^-5 / K × T - 4.13 × 10 ^-2 . Where T is the correlated color temperature 501 while K stands for the unit Kelvin. The first wide upper interval limit 521 is defined by the function 3.91 × 10 ^-5 / K × T + 5.63 × 10 ^-2 . The first middle lower interval limit 530 is defined by the function 1.96 × 10 ^-5 / K × T -2.13 × 10 ^-2 . The first middle upper interval limit 531 is defined by the function 3.91 × 10 ^-5 / K × T + 1.63 × 10 ^-2 . The first narrow lower interval limit 540 is defined by the function 1.96 × 10 ^-5 / K × T-1.30 × 10 ^-3 . The first narrow upper interval limit 541 is defined by the function 3.91 × 10 ^-5 / K × T-2.37 × 10 ^-2 .

A favorable spectrum of the flashlight 120 is at all correlated color temperatures 501 the ambient light 110 defined by its first pro rata spectral power 305 between the first far lower interval limit 520 and the first wide upper interval limit 521 lies. Preferably lies the first proportional spectral power 305 a favorable spectrum 211 between the first middle lower interval limit 530 and the first middle upper interval limit 531 , Particularly preferred is the first proportionate spectral power 305 a favorable spectrum 211 between the first narrow lower interval limit 540 and the first narrow upper interval limit 541 ,

11 shows a second characterization diagram 600 for the further characterization of favorable spectra 211 , On a horizontal axis of the second characterization diagram 600 is in turn the correlated color temperature 501 the ambient light 110 shown. On a horizontal axis of the second characterization diagram 600 is the second proportional spectral power 306 applied. A second lower limit 610 and a second upper limit 611 specify the limits between which the values of the second proportionate spectral power 306 at favorable spectra 211 at different correlated color temperatures 501 according to the above table.

The second lower limit 610 is due to second lower interval limits 620 . 630 . 640 linear approximated. The second upper limit 611 is determined by second upper interval limits 621 . 631 . 641 linear approximated. A second, far lower interval limit 620 is defined by the function 7.55 × 10 ^-6 / K × T + 7.66 × 10 ^-2 . A second wide upper interval limit 621 is defined by the function 9.87 × 10 ^-6 / K × T + 2.08 × 10 ^-1 . A second mean lower interval limit 630 is defined by the function 7.55 × 10 ^-6 / K × T + 9.66 × 10 ^-2 . A second mean upper interval limit 631 is defined by the function 9.87 × 10 ^-6 / K × T + 1.78 × 10 ^-1 . A second narrow lower interval limit 640 is defined by the function 7.55 × 10 ^-6 / K × T + 1.17 × 10 ^-1 . A second narrow upper interval limit 641 is defined by the function 9.87 × 10 ^-6 / K × T + 1.48 × 10 ^-1 .

A favorable spectrum 211 of the flashlight 120 stands out at all correlated color temperatures 501 the ambient light 110 characterized in that its second pro rata spectral power 306 between the second wide lower interval limit 620 and the second wide upper interval limit 621 lies. The second proportional spectral power is preferably located 306 between the second middle lower interval limit 630 and the second middle upper interval limit 631 , Particularly preferred is the second proportionate spectral power 306 a favorable spectrum 211 of the flashlight 120 between the second narrow lower interval limit 640 and the second narrow upper interval limit 641 ,

12 shows a schematic third characterization diagram 700 for the further characterization of favorable spectra 211 of the flashlight 120 at different correlated color temperatures of the ambient light 110 , On a horizontal axis of the third characterization diagram 700 is the correlated color temperature 501 the ambient light 110 applied. On a vertical axis of the third characterization diagram 700 is the third proportional spectral power 307 shown. A third lower limit 710 and a third cap 711 give the limits of the values of the third proportionate spectral power 307 according to the above table at different correlated color temperatures 501 the ambient light 110 at favorable spectra 211 of the flashlight 120 may occur.

A third wide lower interval boundary defined by the function -5.77 × 10 ^-6 / K × T + 1.40 × 10 ^-1 720 approaches the third lower limit 710 linear. A third upper upper interval limit defined by the function -2.06 × 10 ^-5 / K × T + 3.45 × 10 ^-1 721 approaching the third cap 711 linear. A third mean lower interval limit 730 , which is defined by the function -5.77 × 10 ^-6 / K × T + 1.52 × 10 ^-1 , approaches the third lower limit 710 linear. A third mean upper interval limit defined by the function -2.06 × 10 ^-5 / K × T + 3.19 × 10 ^-1 731 approaching the third cap 711 linear. A third narrow lower interval boundary defined by the function -5.77 × 10 ^-6 / K × T + 1.64 × 10 ^-1 740 approaches the third lower limit 710 linear. A third narrow upper interval limit 741 , which is defined by the function -2.06 × 10 ^-5 / K × T + 2.93 × 10 ^-1 , approaches the third upper limit 711 linear.

At all correlated color temperatures 501 the ambient light 110 is a favorable spectrum 211 of the flashlight 120 characterized by having its third proportionate spectral power 307 between the third wide lower interval limit 720 and the third wide upper interval limit 721 lies. The third proportional spectral power is preferably located 307 a favorable spectrum 211 between the third middle lower interval limit 730 and the third middle upper interval limit 731 , Particularly preferred is the third proportionate spectral power 307 a favorable spectrum 211 of the flashlight 120 between the third narrow lower interval limit 740 and the third narrow upper interval limit 741 ,

13 shows a highly schematic representation of a camera 800 , The camera 800 is preferably a digital camera with a digital image sensor 850 , The camera 800 For example, it can be integrated into a mobile telephone or designed as a mobile telephone.

The camera 800 has a lighting device 810 on. The lighting device 810 can also be referred to as a flash device. The lighting device 810 serves to create an environment of the camera 800 at a time to illuminate, with the camera 800 a shot of this environment is made. The lighting device 810 illuminates the environment with light, which is a favorable spectrum 211 according to the definition described above. This will solve with the camera 800 made recordings when viewing a viewer from a color impression, which has only slight deviations from a color impression, the observer receives when looking directly at the photographed environment.

The lighting device 810 has an ambient light detection sensor 820 on, which serves one in the environment of the camera 800 to detect existing ambient light. The ambient light detection sensor 820 is designed to determine a correlated color temperature of the detected ambient light. On the basis of the thus determined correlated color temperature, the lighting device 810 a favorable spectrum for this correlated color temperature of the ambient light 211 determine the flash light.

The ambient light detection sensor 820 can also use the digital image sensor 850 the camera 800 be formed. A separate ambient light detection sensor 820 is not necessary then.

The lighting device 810 further includes a first light emitting diode 830 and a second light emitting diode 840 on. The first light-emitting diode 830 and the second light emitting diode 840 are each designed to emit electromagnetic radiation (visible light) with a defined spectral composition. The spectral composition of the second light emitting diode 840 radiated electromagnetic radiation differs from the spectral composition of the first light emitting diode 830 emitted electromagnetic radiation. The lighting device 810 is designed to be the first light emitting diode 830 and the second light emitting diode 840 to control such that the through the first light emitting diode 830 and the second light emitting diode 840 superimpose emitted electromagnetic radiation such that a resulting total radiation that previously from the lighting device 810 certain favorable spectrum 211 having.

The lighting device 810 can also have more than two light emitting diodes 830 . 840 exhibit. However, it is also possible the lighting device 810 with only one LED 830 train.

The invention has been further illustrated and described with reference to the preferred embodiments. However, the invention is not limited to the disclosed examples. Rather, other variations may be deduced therefrom by those skilled in the art without departing from the scope of the invention.

LIST OF REFERENCE NUMBERS

100

scene

110

ambient light

120

flashlight

130

observer

131

first impression

132

second impression

140

camera

141

color filter

142

White balance

150

monitor

200

RGB filter space diagram

201

red component

202

blue component

210

spectrum

211

favorable spectra

212

mediocre spectra

213

unfavorable spectra

300

first spectrum spectrum related to ambient light

301

rating

302

first relative spectral power

303

second relative spectral power

304

third relative spectral power

305

first proportional spectral power

306

second proportional spectral power

307

third proportional spectral power

310

second ambient light spectrum chart

320

third spectrum diagram related to ambient light

330

first spectrum spectrum spectra

340

second spectrum spectrum spectra

350

third spectrum spectrum spectrum chart

400

spectral

401

wavelength

402

spectral power

500

first characterization diagram

501

correlated color temperature

510

first lower limit

511

first upper limit

520

first wide lower interval limit

521

first wide upper interval limit

530

first middle lower interval limit

531

first middle upper interval limit

540

first narrow lower interval limit

541

first narrow upper interval limit

600

second characterization diagram

610

second lower limit

611

second upper limit

620

second wide lower interval limit

621

second wide upper interval limit

630

second middle lower interval limit

631

second middle upper interval limit

640

second narrow lower interval limit

641

second narrow upper interval limit

700

third characterization diagram

710

third lower limit

711

third upper limit

720

third wide lower interval limit

721

third wide upper interval limit

730

third middle lower interval limit

731

third middle upper interval limit

740

third narrow lower interval limit

741

third narrow upper interval limit

800

camera

810

lighting device

820

Ambient light detection sensor

830

first light-emitting diode

840

second light-emitting diode

850

digital image sensor

Claims (11)

Method for illuminating an environment with electromagnetic radiation, wherein a correlated color temperature ( 501 ) of an ambient light is determined, wherein a spectral power of the electromagnetic radiation is selected so that an integral of the spectral power over a wavelength interval between 380 nm and 780 nm has a nominal value, an integral of the spectral power over a wavelength interval between 420 nm and 460 nm has a first value, an integral of the spectral power has a second value over a wavelength interval between 510 nm and 550 nm, an integral of the spectral power has a third value over a wavelength interval between 580 nm and 620 nm, The relationship ( 305 ) of the first value at the nominal value between the sum of -4.13 × 10 ^-2 and the product of +1.96 × 10 ^-5 / K and the correlated color temperature ( 501 ) and the sum of + 5.63 × 10 ^-2 and the product of + 3.91 × 10 ^-5 / K and the correlated color temperature ( 501 ), the ratio ( 306 ) of the second value at the nominal value between the sum of +7.66 × 10 ^-2 and the product of +7.55 × 10 ^-6 / K and the correlated color temperature ( 501 ) and the sum of +2.08 × 10 ^-1 and the product of + 9.87 × 10 ^-6 / K and the correlated color temperature ( 501 ), and the ratio ( 307 ) of the third value at the nominal value between the sum of +1.40 × 10 ^-1 and the product of -5.77 × 10 ^-6 / K and the correlated color temperature ( 501 ) and the sum of + 3.45 × 10 ^-1 and the product of -2.06 × 10 ^-5 / K and the correlated color temperature ( 501 ) lies. Method according to claim 1, wherein the spectral power of the electromagnetic radiation is chosen such that the ratio ( 305 ) of the first value at the nominal value between the sum of -2.13 × 10 ^-2 and the product of +1.96 × 10 ^-5 / K and the correlated color temperature ( 501 ) and the sum of +1.63 × 10 ^-2 and the product of + 3.91 × 10 ^-5 / K and the correlated color temperature ( 501 ), the ratio ( 306 ) of the second value at the nominal value between the sum of + 9.66 × 10 ^-2 and the product of +7.55 × 10 ^-6 / K and the correlated color temperature ( 501 ) and the sum of +1.78 × 10 ^-1 and the product of +9.87 × 10 ^-6 / K and the correlated color temperature ( 501 ), and the ratio ( 307 ) of the third value at the nominal value between the sum of +1.52 × 10 ^-1 and the product of -5.77 × 10 ^-6 / K and the correlated color temperature ( 501 ) and the sum of + 3.19 × 10 ^-1 and the product of -2.06 × 10 ^-5 / K and the correlated color temperature ( 501 ) lies. Method according to claim 2, wherein the spectral power of the electromagnetic radiation is chosen such that the ratio ( 305 ) of the first value at the nominal value between the sum of -1.30 × 10 ^-3 and the product of +1.96 × 10 ^-5 / K and the correlated color temperature ( 501 ) and the sum of -2.37 × 10 ^-2 and the product of + 3.91 × 10 ^-5 / K and the correlated color temperature ( 501 ), the ratio ( 306 ) of the second value at the nominal value between the sum of +1.17 × 10 ^-1 and the product of +7.55 × 10 ^-6 / K and the correlated color temperature ( 501 ) and the sum of +1.48 × 10 ^-1 and the product of + 9.87 × 10 ^-6 / K and the correlated color temperature ( 501 ), and the ratio ( 307 ) of the third value at the nominal value between the sum of +1.64 × 10 ^-1 and the product of -5.77 × 10 ^-6 / K and the correlated color temperature ( 501 ) and the sum of + 2.93 × 10 ^-1 and the product of -2.06 × 10 ^-5 / K and the correlated color temperature ( 501 ) lies. Lighting device ( 810 ), which is adapted to carry out a method according to one of the preceding claims. Lighting device ( 810 ) according to claim 4, wherein the lighting device ( 810 ) a light emitting diode ( 830 ) having. Lighting device ( 810 ) according to claim 5, wherein the lighting device ( 810 ) at least two light-emitting diodes ( 830 . 840 ) having. Lighting device ( 810 ) according to one of claims 4 to 6, wherein the lighting device ( 810 ) a sensor ( 820 ) for detecting an ambient light. Camera ( 800 ) with a lighting device ( 810 ) according to one of claims 4 to 7. Camera ( 800 ) according to claim 8, wherein the lighting device ( 810 ) is designed as a flash device. Camera ( 800 ) according to one of claims 8 and 9, wherein the camera ( 800 ) a digital image sensor ( 850 ) having. Camera ( 800 ) according to one of claims 8 to 10, wherein the camera ( 800 ) is designed as a mobile phone.

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